Water makes up about three-fourths of Earth's surface. But less than one percent of it can be used by people to drink. Most of the water on our planet is salt water in oceans. People must drink fresh water to live. Drinking seawater causes illness in humans. This is not the case for seagulls. Seagulls can drink seawater or fresh water. Seagulls can live in coastal areas or near lakes and rivers. Seagulls can set out on long trips flying over the ocean. They do not need to return to fresh water for a drink.
Seagulls have a special set of glands right above their eyes called salt glands. These glands rid the extra salt from their systems. When seagulls drink seawater, the salt from the water builds up in the salt glands. The seagull can then get rid of excess salt by "sneezing it out." It is flushed out of openings in the bill. This is why seagulls can go where fresh water is hard to find and still have plenty to drink.
Based on the passage, which of these is most likely true?
A. Humans do not have glands for filtering salt water.
B. Most of the water on earth is drinkable for humans.
C. Seagulls can't fly for a long time in one trip.
D. Humans must drink salt water to live.